1. Field of the Invention
The present invention relates to a cooling system for an ocular infusion solution and, more particularly, to a cooling system including a detachable, reusable chilling cassette which receives, cools, and dispenses ocular infusion solution to a destination site.
2. Description of Related Art
The art of transporting an ocular infusion solution to the human eye is generally cognizant of pumps and heat exchangers which may be used together for anterior chamber perfusion. Representative prior art in the field of transporting an ocular infusion solution is included below.
A 1983 British Journal of Ophthalmology article, "Ocular Hypothermia: Anterior Chamber Perfusion" by May et al., discloses the application of a saline solution to a rabbit eye wherein a heat pump and a temperature controller are utilized.
U.S. Pat. No. 2,124,293 teaches the broad concept of using a temperature controller to regulate the temperature of an infused fluid. Similarly, U.S. Pat. No. 4,249,923 discloses a refrigeration and delivery system for chilling a cardioplegic fluid to a predetermined temperature. U.S. Pat. No. 4,929,134 discloses a thermoelectric chiller in a cardiac application. Lastly, U.S. Pat. No. 4,734,091 teaches a filtered manifold apparatus and method of ophthalmic irrigation.
The need for an improved cooling system for ocular infusion solutions still exists, particularly in view of new surgical techniques which may probe deeper into the eye and require several hours of operating time. Surgical advances now permit surgery in the vitreous (posterior) chamber to remove opacified vitreous humor or to repair retinal detachment. Such operations require significant time, e.g., one to three hours, and large volumes of irrigating solution, e.g., 100-1000 ml.
During eye surgery and, particularly, during surgery which requires extended periods of time, proper electrolytic balance alone is insufficient to retain normal corneal thickness. To maintain proper corneal thickness and prevent cell damage, an irrigating solution, in addition to electrolytic balance, must provide metabolic support.
Although several cooling systems for infusion solutions exist, the art is still without an inexpensive cooling system that is simple to operate, features the added convenience of a detachable, reusable heat exchanger element (i.e., chilling cassette), permits the evacuation of air bubbles from the ocular infusion solution as the solution is being cooled, and delivers the infusion solution to the irrigation site at a controlled and predetermined temperature.